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Glucocorticoids are important therapy for acute lymphoblastic leukemia (ALL) and their major adverse effect is osteonecrosis. Our goal was to identify genetic and nongenetic risk factors for osteonecrosis. We performed a genome-wide association study of single nucleotide polymorphisms (SNPs) in a discovery cohort comprising 2285 children with ALL, treated on the Children's Oncology Group AALL0232 protocol (NCT00075725), adjusting for covariates. The minor allele at SNP rs10989692 (near the glutamate receptor GRIN3A locus) was associated with osteonecrosis (hazard ratio = 2.03; P = 3.59 × 10(-7)). The association was supported by 2 replication cohorts, including 361 children with ALL on St. Jude's Total XV protocol (NCT00137111) and 309 non-ALL patients from Vanderbilt University's BioVU repository treated with glucocorticoids (odds ratio [OR] = 1.87 and 2.26; P = .063 and .0074, respectively). In a meta-analysis, rs10989692 was also highest ranked (P = 2.68 × 10(-8)), and the glutamate pathway was the top ranked pathway (P = 9.8 × 10(-4)). Osteonecrosis-associated glutamate receptor variants were also associated with other vascular phenotypes including cerebral ischemia (OR = 1.64; P = 2.5 × 10(-3)), and arterial embolism and thrombosis (OR = 1.88; P = 4.2 × 10(-3)). In conclusion, osteonecrosis was associated with inherited variations near glutamate receptor genes. Further understanding this association may allow interventions to decrease osteonecrosis. These trials are registered at www.clinicaltrials.gov as #NCT00075725 and #NCT00137111.
© 2015 by The American Society of Hematology.
We conducted a nested case-control study within a cohort of 6244 patients to assess risk factors for avascular necrosis (AVN) of bone in children and adolescents after allogeneic transplantation. Eligible patients were ≤21 years of age, received their first allogeneic transplant between 1990 and 2008 in the United States, and had survived ≥ 6 months from transplantation. Overall, 160 patients with AVN and 478 control subjects matched by year of transplant, length of follow-up and transplant center were identified. Patients and control subjects were confirmed via central review of radiology, pathology, and/or surgical procedure reports. Median time from transplant to diagnosis of AVN was 14 months. On conditional logistic regression, increasing age at transplant (≥5 years), female gender, and chronic graft-versus-host disease (GVHD) were significantly associated with increased risks of AVN. Compared with patients receiving myeloablative regimens for malignant diseases, lower risks of AVN were seen in patients with nonmalignant diseases and those who had received reduced-intensity conditioning regimens for malignant diseases. Children at high risk for AVN include those within the age group where rapid bone growth occurs as well as those who experience exposure to myeloablative conditioning regimens and immunosuppression after hematopoietic cell transplantation for the treatment of GVHD. More research is needed to determine whether screening strategies specifically for patients at high risk for developing AVN with early interventions may mitigate the morbidity associated with this complication.
Copyright © 2014 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.
Patients undergoing glucocorticoid therapy for a variety of disorders, including autoimmune diseases and hematological malignancies, are at risk of developing osteonecrosis. Despite extensive research in both patients and animal models, the underlying pathogenesis remains unclear. Proposed inciting mechanisms include intravascular thrombotic occlusion, marrow fat hypertrophy, osteocyte and/or endothelial cell apoptosis, hypercoagulability, and vasoconstriction of specific arteries and arterioles supplying bone. Our laboratory has developed a model of steroid-induced osteonecrosis in BALBcJ mice which reflects clinically relevant exposures to glucocorticoids in which treated mice develop osteonecrosis of the distal femoral epiphysis when administered 4 to 8 mg/L dexamethasone in drinking water for 6 weeks. We identified lesions in arterioles supplying this area, with the mildest occurring in knees without any evidence of osteonecrosis. However, arteriopathy was more common among mice that did versus did not develop osteonecrosis (P < 0.0001); in mice with osteonecrosis, the associated vessels showed transmural necrosis and thickening of the vessel wall progressing to the point of luminal obstruction. In the most severe cases of osteonecrosis, end-stage lesions consisted of fully occluded vessels with marrow and bone necrosis involving the entire epiphysis. We propose that a primary arteriopathy is the initiating event in the genesis of steroid-induced osteonecrosis and provides a basis for future investigation of this disease process.
Copyright © 2013 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
We previously reported strain-specific susceptibility to dexamethasone-induced osteonecrosis in mice. Here we report that BALB/cJ and BALB/cAnNHsd mice display substrain-specific differences in dexamethasone-induced adverse effects. As compared with BALB/cJ mice, BALB/cAnNHsd weighed more (16.6 g compared with 13.7 g) at the beginning of dexamethasone administration on postnatal day 28 and fewer died during the dexamethasone regimen (10% compared with 50%). Although the 2 substrains had similar plasma concentrations of dexamethasone, BALB/cJ mice were more susceptible to developing dexamethasone-induced osteonecrosis. A higher dose of dexamethasone (8 mg/L) throughout the treatment period compared with a lower dose (8 mg/L loading dose during week 1 followed by 4 mg/L for the remainder of the treatment period) and earlier start of treatment (postnatal day 24 compared with postnatal day 28) was required to induce osteonecrosis with a similar frequency in BALB/cAnNHsd mice as in BALB/cJ mice. Our results show, for the first time, substrain-specific differences in the development of osteonecrosis in mice.
Radiation related effects in children and adults limit the delivery of effective radiation doses and result in long-term morbidity affecting function and quality of life. Improvements in our understanding of the etiology and biology of these effects, including the influence of clinical variables, dosimetric factors, and the underlying biological processes have made treatment safer and more efficacious. However, the approach to studying and understanding these effects differs between children and adults. Using the pulmonary and skeletal organ systems as examples, comparisons are made across the age spectrum for radiation related effects, including pneumonitis, pulmonary fibrosis, osteonecrosis, and fracture. Methods for dosimetric analysis, incorporation of imaging and biology as well a length of follow-up are compared, contrasted, and discussed for both organ systems in children and adults. Better understanding of each age specific approach and how it differs may improve our ability to study late effects of radiation across the ages.
Glucocorticoid-induced osteonecrosis is a common and dose-limiting adverse event. The goal of this study was to establish a mouse model of glucocorticoid-induced osteonecrosis suitable for testing the effects of different treatment strategies on its frequency. Fourteen murine strains were screened using various glucocorticoids, routes of administration, and diets. Four-week-old male BALB/cJ mice were treated with oral dexamethasone for up to 12 weeks either by continuous dosing or by discontinuous dosing, with or without asparaginase. Histopathological features of the distal femurs were examined by light microscopy. Osteonecrotic lesions were characterized by empty lacunae and osteocyte ghosts in trabecular bone surrounded by necrotic marrow and edema. The incidence of dexamethasone induced osteonecrosis in BALB/cJ mice was 40-45% (4/10 or 5/11) at 12 weeks. The frequency of osteonecrosis trended lower after discontinuous compared to continuous dosing for 12 weeks (8 vs. 45%) (p = 0.06) despite comparable cumulative plasma exposure. Asparaginase hastened the occurrence of osteonecrosis, which was observed as early as 4 weeks and the incidence was 50% after 6 weeks. A mouse model of glucocorticoid-induced osteonecrosis was established. Discontinuous was less osteonecrotic than continuous dexamethasone treatment, consistent with the possible benefits of a "steroid holiday" seen in clinical settings. Moreover, asparaginase hastened osteonecrosis, indicating that drugs may interact with glucocorticoids to affect osteonecrosis risk.